The present invention generally relates to methods and apparatuses for probing semiconductor circuits, and more specifically relates to a method and apparatus for probing semiconductor circuits using a wafer-mounted micro-probing platform.
Failure analysis, design debugging and process/device characterization of a semiconductor circuit is typically performed using probes. Specifically, probes are used to probe semiconductor circuits to gain electrical information about the circuit under test. Mechanical connection to the circuit is typically achieved using small metal probes. The probes are maneuvered into place with probe manipulators, which provide that the probes can be precisely positioned and oriented.
Existing mechanical probing technology uses a platform (i.e., platen) separated from the wafer to hold the probe manipulators and probes. This facilitates probing many die on the wafer by moving the wafer independent of the platen. The probes are positioned in the spatial arrangement required to contact the areas of interest. When moving from one die to the next, the probes are lifted (i.e., separated from the die), the wafer is spatially translated to the next die of interest, and the probes are lowered into contact with the die. Many die may be probed in this manner without having to stop and re-arrange the probe positions for each new die.
The main problem with the probing arrangement discussed above is the extra spatial requirements necessary to support and place the probe manipulators. Under normal probing situations, this is not an issue, as probing is conducted on a dedicated probe station. However, new process technology improvements are driving feature sizes smaller and smaller. The smaller the feature sizes become, the more difficult it is to physically contact them using a conventional probe station.
The advent of active and passive contrast and test/yield/quality vehicles designed for use with SEM/FIB-based contrast mechanisms is driving the need to be able to probe semiconductor circuits in the vacuum chamber. In other words, there is a need for an in-vacuum chamber probing solution. While there are several in-vacuum chamber probing systems which are presently commercially available (such as Schlumberger IDS systems), the systems which are available require retrofitting a vacuum chamber of a SEM/FIB, and are generally very expensive, low SEM resolution solutions.
Generally, the solutions which are commercially available or are widely used require either the use of a dedicated vacuum chamber (i.e., a vacuum chamber which is designed specifically for probing) or require retrofitting the vacuum chamber of the SEM/FIB to be used in conjunction with probing. Both approaches require a relatively significant cost in materials and tool downtime for setup and takedown of the probing system, during which time the tool is unavailable for other use. The approaches require significant capital investment in that a probe station must be purchased, a dedicated vacuum chamber/SEM must be purchased (if applicable), and probe manipulators must be purchased.